Muscle Actions - Vocab Terms

Front

What is Circumduction?

Back

Circumduction is a circular movement of a limb, where the proximal end remains stationary while the distal end moves in a circular path. It is commonly seen in shoulder and hip joints.

Front

What is Plantar Flexion?

Back

Plantar flexion is the action of pointing the toes away from the shin, typically performed when standing on tiptoes or pushing the gas pedal in a car.

Front

What is Inversion?

Back

Inversion is the movement that turns the sole of the foot medially, bringing the inner edge of the foot closer to the midline of the body.

Front

What is Extension?

Back

Extension is the action of straightening a joint, which increases the angle between the bones involved. An example is the triceps brachii straightening the forearm.

Front

What is a Synergist?

Back

A synergist is a muscle that assists another muscle (the prime mover) in performing a movement. For example, the temporalis acts as a synergist to the masseter in closing the jaw.

Front

What is Flexion?

Back

Flexion is the action of bending a joint, which decreases the angle between the bones. An example is bending the elbow.

Front

What is Rotation?

Back

Rotation is the movement of a body part around its own axis. An example is turning the head from side to side.

Front

What is Eversion?

Back

Eversion is the movement that turns the sole of the foot laterally, moving the outer edge of the foot away from the midline of the body.

Front

What is a Prime Mover?

Back

A prime mover, or agonist, is the muscle that is primarily responsible for a specific movement. For example, the biceps brachii is the prime mover for elbow flexion.

Front

What is a Fixator?

Back

A fixator is a muscle that stabilizes a joint or body part, allowing other muscles to act more effectively. An example is the rotator cuff muscles stabilizing the shoulder joint.